Patent US4523494A successfully refreshed from Google Patents.
US4523494A
Expired / Lapsed
US
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Steering pressure responsive differential lock control system
Assignee: Deere and Co
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Filing: 1983-06-13
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Granted: 1985-06-18
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Expires: 2003-06-13
Abstract
Abstract A differential lock control system includes a solenoid valve which operates hydraulic differential lock mechanisms in response to the operation of a control circuit. The control circuit includes normally closed, steering-responsive switches which open to unlock the differential when steering effort exceeds a certain level. The steering-responsive switches are operated by pins which are exposed to pilot pressures on either end of a valve spool of a conventional pilot-operated steering valve.
Inventors
- 👤 Gregory E. Sparks
- 👤 David A. Larson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:39
CPC Classifications
B; B60; B60K; B60K23/00; B60K23/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
94 words
In a vehicle having an hydraulic steering system including a pilot pressure-operated steering valve, a differential and a steering-responsive differential lock control system, including locking means for locking and unlocking the differential, the improvement wherein the steering-responsive differential lock control system comprises: a pressure-operated normally closed switch mounted at an end of a housing of the steering valve and acted upon by a pilot pressure which acts upon an end of a valve spool of the steering valve, the pressure-operated switch open to unlock the differential when the pilot pressure exceeds a predetermined pressure.
Claim 2
Dependent Claim
94 words
In a vehicle having an hydraulic steering system including a pilot pressure-operated steering valve, a differential and a steering-responsive differential lock control system, including locking means for locking and unlocking the differential, the improvement wherein the steering-responsive differential lock control system comprises: a pressure-operated normally closed switch mounted at an end of a housing of the steering valve and acted upon by a pilot pressure which acts upon an end of a valve spool of the steering valve, the pressure-operated switch open to unlock the differential when the pilot pressure exceeds a predetermined pressure.
Claim 3
Dependent Claim
43 words
The invention of claim 1, wherein the control system comprises: a further pressure-operated switch mounted at an opposite end of the housing of the steering valve and operated upon by a pilot pressure which acts upon an opposite end of the valve spool.
Claim 4
Dependent Claim
109 words
The control system of claim 2, further comprising: a potential source; a normally open latching relay having a double pole switch having a common side of both poles connected to the potential source, the other side of one pole being coupled to the locking means, having a relay coil for closing the double pole switch, the relay coil having a first terminal grounded and a second terminal, the second terminal being coupled to the other side of the other pole via the pressure-operated switches, the pressure-operated switches being connected in series, the control system controlling the locking means in response to operation of the relay and the pressure-operated switches.
Claim 5
Dependent Claim
24 words
The control system of claim 3, further comprising: a normally open momentary contact switch coupled between the potential source and the second coil terminal.
Claim 6
Dependent Claim
105 words
The control system of claim 1, wherein the pressure-operated switch comprises: a hollow switch housing mounted at an end of the steering valve housing and having a bore which opens into a pilot chamber of the steering valve; a pin slidable in the bore and exposed to pilot pressure in the pilot chamber; a snap-acting switch mounted in the switch housing and operatively engaging an end of the pin; and resilient means biased to urge the pin away from the snap-acting switch and in opposition to the pilot pressure, the pin moving to toggle the snap-acting switch when the pilot pressure exceeds the predetermined pressure.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-17 | 1988-12-17 | 1989-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-17 | 1992-12-17 | 1993-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-17 | 1996-12-17 | 1997-06-18 | $7700.00 | Window Closed / Lapsed |